1. Field of the Invention
The field of the invention is electronic controls for controlling electrical equipment, such as electric motors, where an electrical current is sensed and then compared to a current command to arrive at a resulting signal to be applied to the motor. The invention may also have application to other types of controls in which current sensing is important.
2. Background Art
An example of an electronic control for a DC motor is shown and described in Berkopec et al., U. S. Pat. No. 4,549,122, issued Oct. 25, 1985. A basic function of the control is to regulate armature current by sensing the actual current fed to the armature and by determining the difference between this signal and a current command signal. The difference between these two signals becomes an error signal that is applied to the motor through an armature current regulating amplifier to reduce the error or difference between the two signals.
Current sensing in this type of motor control has typically been accomplished with some type of analog circuitry. The application of digital microprocessors to this type of motor control has offered advantages in fast response time in executing motor control loops. The use of such digital circuits, however, requires new digital techniques for sensing the voltages and currents present in electrical motors.